@ScottJ1 and @CccA many thanks for your posts. I ran into this exact same issue this morning. Parallels 11, Windows 10 - both up to date with patches.
I dug into the issue a bit, and it is clear that the cause is because the edb.log file is somehow corrupt. It turns out that this file is the redo log for the Microsoft Extensible Storage Engine - aka database manager. The ESE technology, which has been around for a while and seems to have been used extensively in Exchange and Active Directory, seems to also be in use by Windows 10 for storing information regarding the Live Tiles that make up the Start Menu/Screen. It seems to be used for other things too. On searching for edb.log in the AppData folder I found 9 instances of this file. I surmise that this database/storage technology is being used in these places:
C:\Users\%USERNAME%\AppData\Local\Microsoft\Windows\SettingSync\metastore
C:\Users\%USERNAME%\AppData\Local\Microsoft\Windows\SettingSync\remotemetastore\v1
C:\Users\%USERNAME%\AppData\Local\Packages\Microsoft.Windows.Cortana_cw5n1h2txyewy\AppData\Indexed DB
C:\Users\%USERNAME%\AppData\Local\TileDataLayer\Database
C:\Users\%USERNAME%\AppData\Local\Packages\Microsoft.MicrosoftEdge_8wekyb3d8bbwe\AC\MicrosoftEdge\User\Default\DataStore\Data\nouser1\120712-0049\DBStore\LogFiles
C:\Users\%USERNAME%\AppData\Local\Packages\Microsoft.ZuneMusic_8wekyb3d8bbwe\LocalState\Database\anonymous
C:\Users\%USERNAME%\AppData\Local\Packages\Microsoft.MicrosoftEdge_8wekyb3d8bbwe\AppData\User\Default\Indexed DB
C:\Users\%USERNAME%\AppData\Local\Packages\Microsoft.ZuneVideo_8wekyb3d8bbwe\LocalState\Database\9caa64314892cc5e
C:\Users\%USERNAME%\AppData\Local\Microsoft\Internet Explorer\Indexed DB
From my research on the web, it appears that some others (presumably non-Parallels users) are also experiencing this issue - Start Menu not working, Cortana not working, Microsoft Edge not working.
Among these the following solutions seemed to have helped some:
1. Resetting the App-Packages
Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}
2. Resetting the Theme
Change the current Theme to some High-Contrast theme, log out, log back in, and viola the problem is fixed.
3. Creating a new user, and using that new user instead of the old one.
In all these 3, notice that the edb database is involved based on my list of its instances I found above. I think the associated fixes all have to do somehow with fixing this corrupt database.
In #1 the database that stores the Packages (list of Apps - esp. Modern Apps that make up the Tiles) is being rebuilt through a fix using the Powershell:
In #2 the database that presumably stores cross-device Settings (Wallpaper, Desktop Theme etc.) probably somehow gets rebuilt by changing the Theme and then restoring it.
In #3 obviously both the Package List, the SyncSettings and the Live Tiles database all get a nice clean new database. In our case in this thread we were dealing with just the Live Tiles Data Layer (Start Menu/screen), but it could apply to other aspects that use the ESE edb.log file as well.
Given all this, I find it difficult to believe that this is an issue with Parallels. If it were somehow related to Parallels not writing a file properly, we would expect to see similar issues with a whole bunch of other files. The fact that it has to do with the ESE and the edb.log, suggest that this is a Microsoft bug.
For what it is worth, my issues started this morning and I first noticed Microsoft Edge icon disappearing. Also the whole system was sluggish. Upon quickly bringing up Task Manager, I noticed that O365 Click-to-run process (forget the exact name) was very busy, consuming a good amount of CPU. Now, I also had customized my Live Tiles to put the O365 apps on them (recently updated to Office 2016). This might well be one of the culprits in causing the edb.log file to become corrupt.
I think what is lacking is proper control over multiple processes accessing this edb.log file simultaneously. I suspect this because I also see some Errors in my event log indicating that one process was not able to access it because it was in use:
SettingSyncHost (4924) {09562336-B1FE-4705-AE17-25602A3F0924}: An attempt to open the file "C:\Users\arun\AppData\Local\Microsoft\Windows\SettingSync\metastore\edb.log" for read only access failed with system error 32 (0x00000020): "The process cannot access the file because it is being used by another process. ". The open file operation will fail with error -1032 (0xfffffbf8).
In my case it could well be that the O365 Click-to-run process was stomping on some other process (perhaps even user click on the Start Menu) that was trying to use the edb.log.
I hope the Parallels Engineering team in Seattle has an inside line into Microsoft Engineering to be able to pass on this info and report back to us on what exactly the issue is. Please don't use this post as a way to say it is not a Parallels issue. Please follow through on it with your engineering team and Microsoft.
For anyone encountering such issues, your first step should be to check the Windows logs using Event Viewer. Look for errors relating to edb.log. If you find any, make note of the path to the file, and that should give you a clue to which aspect is corrupt and needs to be reset with a new database or by getting a copy of the folder from a backup.
There apparently is also a way to repair these database files using a utility called esentutl (you can invoke it in command prompt) and running various commands including checking the health, defragmenting, repairing etc. I didn't dig too much into it, because the best way seems to reset the entire database with new or old backup.
I ended up using the wonderful instructions that CccA and ScottJ1 provided. I also reset my packages using the Powershell as listed above - this helped reset the icons for Microsoft Edge. I suggest that this is a good option to do - harmless rebuild of the Pacakges database.
